This invention relates to a graphical display generating system and a method of generating a graphical display for modelling true to scale three dimensional objects on a two dimensional graphical display.
The invention has particular utility in computer aided design (CAD) applications for technical and architectural drawing or modelling as well as other applications where 3-D data needs to be input quickly and interactively.
Present CAD systems are not practically adapted for pure technical and architectural drawing requirements, and although such systems find utility with graphic artists and designers, due to their complexity they have not been widely accepted by technical draftsmen and architects for the production of technical and engineering drawings of measured three dimensional objects.
In general, the problems associated with inputting measured three dimensional data using current three dimensional CAD software programmes/systems are:
(i) The drawing process is extremely complicated.
(ii) Three dimensional CAD software programs cannot move the cursor/pointer through the three dimensional space leaving a trail behind which represents a measured line and draw with six degrees of freedom inside the three dimensional space.
(iii) Current three dimensional CAD software programs do not permit information to be inputted directly in three dimensional form by, using a cursor/pointer and maintain on screen:
A. real measured drawings/data
B. the operator knowing where he is at all times, and
C. knowing the distance from one object to another, without reference to two dimensional plans, sections or elevations.
(iv) They consume an enormous amount of time in entering measured data and creating a true to scale three dimensional image on a two dimensional screen.
It is an object of the present invention to provide an improved and simpler system and method of entering measured three dimensional data and creating a two dimensional image of a true to scale three dimensional object which overcomes or at least mitigates some, if not all, of the aforementioned disadvantages associated with CAD systems.
In accordance with a first aspect of the present invention, there is provided a graphical display generating system for modelling measured three dimensional objects on a two dimensional graphical display, the system comprising:
input means for generating raw data representative of discrete three dimensional points of said object;
first processing means for receiving and processing said raw data from said input means by transposing said raw data into processed data representative of said discrete points in a three dimensional spatial array, the transposition being performed in accordance with a first mathematical algorithm;
second processing means for receiving and further processing said processed data by transforming said processed data into display data representative of said discrete points in a two dimensional display array, the transformation being performed in accordance with a second mathematical algorithm; and,
display means for graphically displaying the image represented by said display data in said two dimensional display array.
Preferably, said first mathematical algorithm comprises a transposition of data to three dimensional cartesian co-ordinates.
Preferably, said second mathematical algorithm comprises a transformation of data in three dimensional cartesian co-ordinates to two dimensional oblique co-ordinates using the formulae:
Display X=Processed X+(Processed Zxc3x97(a/m))
Display Y=Processed Y+(Processed Zxc3x97(b/m));
where:
Display X is the abscissa and Display Y is the ordinate of the display data,
Processed X, Processed Y and Processed Z are the corresponding abscissa, ordinate and Z-axis components of the processed data, and
m, a and b are the projection parameters for the display data where m is the scale for the X and Y co-ordinates of the display data, a is the abscissa component of the Z-axis projection of the display data, and b is the ordinate component of the Z-axis projection of the display data.
Preferably, said system further includes a database means for receiving and storing said processed data in a prescribed data structure.
Preferably, said second processing means receives said processed data from either said first processing means or said database means.
Preferably, said prescribed data structure is a two dimensional array in the form of a look-up table.
Advantageously said input means comprises cursor positioning means for moving a cursor on a two dimensional simulation of measured three dimensional space.
In accordance with another aspect of the present invention, there is provided a method of generating a graphical display for modelling three dimensional objects on a two dimensional graphical display, the method comprising the steps of:
generating raw data representative of discrete three dimensional points of said object;
transposing said raw data into processed data representative of said points in a three dimensional spatial array in accordance with a first mathematical algorithm;
transforming said processed data into display data representative of said discrete points in a two dimensional spatial array in accordance with a second mathematical algorithm; and
graphically displaying said display data in said two dimensional spatial array.
Preferably, said first mathematical algorithm comprises a transposition of data to three dimensional cartesian co-ordinates.
Preferably, said second mathematical algorithm comprises a transformation of data in three dimensional cartesian co-ordinates to two dimensional oblique co-ordinates using the formulae:
Display X=Processed X+(Processed Zxc3x97(a/m))
Display Y=Processed Y+(Processed zxc3x97(b/m));
where:
Display X is the abscissa and Display Y is the ordinate of the display data, processed X, Processed Y and Processed Z are the corresponding abscissa, ordinate and Z-axis components of the processed data, and m, a and b are the projection parameters for the display data where m is the scale for the X and Y co-ordinates of the display data, a is the abscissa component of the Z-axis projection of the display data, and b is the ordinate component of the Z-axis projection of the display data.